Very often we are asked to provide expected visitor volumes from the core target keywords of an SEO campaign. Of course, we explain the ‘long tail' and the fact that many hundreds if not thousands of keywords will potentially be referring visitors, but it enables the client to quantify their investment by getting some gauge on expected sales and ROI. From the point of view of an SEO however, it can be quite tricky to explain the ‘pinch of salt' aspect of any such estimates, and that there are no guarantees. It is a fine balancing act for SEO agencies – avoiding the ‘you said we would get 1000 visitors being #1 and we're getting 100' scenario is a must. Ensuring as high a level of accuracy as possible when estimating volumes is therefore also a must.

We have historically used a combination of the following tools and methods to gauge potential traffic volumes from natural search:

o Google Adwords / MSN AdCenter / Yahoo traffic estimators

o Online tools such as Keyword Discovery, Wordtracker, Wordze etc

o Existing PPC / Organic search analytics data

o Creating temporary PPC campaigns to test volumes

o Google Trends

Google Trends has always been useful to look at comparative volumes – for example, we often use it to see whether the singular or plural of a keyword is more popular. Beyond this, it has always been quite limited. A recent Google Trends update however, could revolutionise the forecasting of organic search traffic.

Now that's all well and good but it still doesn't help in estimating traffic for those terms, so how do you do that? Well, any worthwhile SEO agency should have a decent portfolio of #1 rankings for relatively high volume search terms. I would also expect them to have a decent analytics package in place on their clients' sites, from which you can monitor the traffic those #1 rankings generate. This is key.

You may have already achieved a #1 position for ‘blue widgets', and so are thinking about expanding your keyword list to include ‘yellow widgets'. You already know how many visitors your ‘blue widgets' success is worth, so now use Google Trends to compare volumes with ‘yellow widgets'. If ‘blue widgets' generates 100 visits per day, and Trends tells you that ‘yellow widgets' is 0.6 of the volume, you know to expect 60 visits per day from a #1 position for ‘yellow widgets'. Useful eh!

This is great because it is sector independent. Your results will not lose accuracy if you are comparing a keyword from one sector to a keyword from another.

Of course, number 1's can take time to achieve – particularly for competitive keywords and relatively unestablished sites. It can often be useful therefore, to provide keyword traffic forecasts for other first page positions. How? By making use of the notoriously leaked AOL click through data. Knowing that a #2 ranking is worth x% of the visitors of #1, #3 worth x-1% etc you can quickly build up a list of visitor volumes for each of the top 10 positions, by keyword.

Any such forecasts are however just that. Forecasts, estimations, approximations. We always allow for a small variance due to influences on Click Rate (CTR) from the SERPS. Typical influencing factors are:

o Brand Terms – Brand searches typically get a higher CTR.

o Long Tail Searches vs Generic Searches – Long tail searches generally result in a higher CTR because the searcher is further through the ‘search cycle'. They know exactly what they are looking for and so are more likely to click a search listing.

o Titles and Meta Descriptions – more compelling search listing ‘creative' usually sees a higher CTR than something bland and uninviting.

o PPC ads – Generally speaking, the more PPC ads that are present on a page (especially at the top) the lower CTR the natural results will receive.

While these factors may, to a certain extent skew your results, our SEO traffic forecasting tests using Google Trends always maintain a decent level of accuracy.

The upgrade of Google Trends has many positive implications and is a huge help to anyone involved in search marketing, so thanks Google! It's nice to see a development that actually helps rather than hinders us SEOs!